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High Fire Performance of DELTABEAM® Slim Floor Joints with Timber Slabs

By Salla-Mari West

January, 18, 2023

The use of mass timber products like cross-laminated timber (CLT) slabs have become more popular. As an industry forerunner Peikko’s aims to increase safety, speed, space, and sustainability by offering the best combination of different materials. 

DELTABEAM® Slim Floor Structure used together with CLT slabs has high fire resistance without the need for any additional fire protection. Based on experience and performed fire tests Peikko can support its customers to meet the future needs and design effectively also in fire situation.

Peikko has been investigating the performance of the joint area between DELTABEAM® Composite Beam and timber floors to fill the gaps in standards with facts. Joints require careful design especially in fire situation. For us it is important that our customers can rely on our promise for safe and proofed solutions. DELTABEAM® enables to create a slim floor structure while simultaneously joining the beam and CLT slab together with encapsulated transverse reinforcement.

Charring test and 90-minute fire test with loading were performed for DELTABEAM® Composite Beam with CLT slab structure. The specimen for the charring test had seven different details which were equipped with thermocouples. DELTABEAM® Composite Beam was not fireproofed in any of the cross-sections. The load arrangement in the 90-minute fire test simulated DELTABEAM® and CLT slab structure with 8 m CLT span, 1.7 kN/m2 permanent load and 5 kN/m2 live load in congregation, shopping areas, or F traffic areas.

Due to the protecting effect of the DELTABEAM® ledge, the infill concrete and Peikko’s unique solution the charring depth proved to be smaller in the joint area than in the middle of the CLT span. DELTABEAM® had no negative impact on the charring rate of the CLT panel in any of the tested cross-sections. Based on the fire test results the load transfer works as assumed in the DELTABEAM® design. All REI90 requirements were met. Results showed clearly that Peikko’s design concept for DELTABEAM® Slim Floor Structure with CLT slabs works without any additional fire proofing under the beam nor under the CLT slabs. DELTABEAM® temperatures in the fire tests were clearly on the safe side compared to the temperatures used in DELTABEAM® design.

White Paper - High Fire Performance of DELTABEAM® Slim Floor Joints with Timber Slabs


Salla-Mari West

R&D Engineer
Peikko Group Corporation

Simo Peltonen

Senior R&D Manager
Peikko Group Corporation

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